This invention relates to an improved piston ring seal in squeeze film shaft dampers for rotating machinery such as hot gas turbine engines, and more particularly to an improved piston ring seal having radial and axial pressure force compensating characteristics to maintain sealing under varying pressure conditions.
A squeeze film damper generally includes a thin annular space between a moveable bearing support and its housing. Oil under pressure is introduced into the annular space to limit support motion. Piston ring type seals are employed at each side of the annular space to provide fluid sealing. Ordinarily those piston ring seals depend on certain circumferentially distributed pressure forces for effective sealing. However, fluid pressures employed for ring sealing in a squeeze film damper are not distributed equally circumferentially and their variation may cause unseating of the ring seals with resulting excessive fluid leakage. Furthermore, since piston ring seals are easily reversed during assembly, judicious caution must be exercised in providing any modifications in the ring structure which, if the ring is improperly installed may cause rapid failure of the damper.